A pay-as-you-go country or a PayGo country is one where you are charged a very high rate for using data, voice and SMS.
To avoid bill shock, we deactivate your data as soon as we receive a report notifying us of your location. So although you cannot use data in these PayGo countries, Voice and SMS are still available admittedly at very high rates.
So, if you choose to use Voice or SMS while in a PayGo country, you will be charged based on the rates in that country.
We highly recommend that you not use Voice nor SMS while traveling abroad to save on your International Roaming charges.